1. Field of Invention
The present invention relates to a bi-power motor controlling system and a motor controlling apparatus thereof that can reduce the current and thus improve the noise problem.
2. Related Art
As shown in FIG. 1A, a conventional motor controlling system 1A mainly includes a driver 10 and a coil 11, which is electrically connected with the driver 10. The driver 10 is electrically connected with a power generator 12 for receiving a power VCC from the power generator 12. Then, the driver receives the desired operation voltage from the power VCC and outputs a driving current to the coil 11 accordingly.
In addition, FIG. 1B discloses another conventional motor controlling system 1B, which is different from the above-mentioned motor controlling system 1A in that the driver 10 of the motor controlling system 1B is electrically connected with a plurality of coils 11 (FIG. 1B shows two coils 11).
Both of the conventional motor controlling systems 1A and 1B control the rotational speed of the motor by changing the power VCC. However, this kind method for controlling the rotational speed is limited by the operation voltage of the driver 10, which uses the same power source, so that the controllable rotational-speed range is too narrow. Thus, it is gradually unable to satisfy the demands of industry.